Objective To elucidate the genetic characteristics and variations of glycosylation sites of neuraminidase (NA) gene of the novel A/H1N1 influenza pandemic virus in 2009. Methods The sequences of NA gene of 110 A/H1N1 influenza virus strains isolated at different time and locations were downloaded from NCBI database. MEGA4.0 software and NJ method were used for nucleotide sequence alignment, coding protein sequence alignment and the phylogenetic tree construction. Results The NA gene of the novel A/H1N1 influenza virus strains isolated from different areas in 2009 shared an extremely high homology of 99. 5%-100%, but it was different from that of A/human/H1N1 influenza virus. The novel A/H1N1 influenza virus strains and Europe A/swine/HlNl influenza virus strains shared a high homology of 89. 6% - 92. 9%, with similar glycosylation sites at 50, 58, 63, 68, 88, 146, 235 and 386. Moreover, the homology of NA gene between the novel A/H1N1 influenza virus and A/chicken/H5N1 influenza virus amounted to 83. 6% -85. 3%. Amino acid residues at the enzyme active sites of the NA were strictly conservative in most novel A/H1N1 influenza virus strains, still manifesting as R118, D151, R152, R225, E277, R293, R368, Y402, E119, R156, W179, S180, D199, 1223, E228, H275, E278, N295 and E425. Four strains isolated from Denmark, Japan, and HongKong and Hunan province showed a H275Y mutatioa The NA gene of the novel A/H1N1 influenza virus might originate from Europe A/swine/HlNl influenza virus, and had genetic relationship with A/ chicken/H5N1 influenza virus. Conclusions The novel A/H1N1 influenza pandemic virus in 2009 might be a reassorted virus rather than the result of gradual evolution of A/human/HlNl influenza virus. A novel A/H1N1 influenza virus strain isolated from Hunan has a H275Y mutation which might be oseltamivir resistant.%目的 探讨2009年新型甲型H1N1流感病毒神经氨酸酶(NA)基因的进化规律,分析NA蛋白酶活性位点以及糖基化位点变化情况.方法 从NCBI检索获得110株不同年代、不同地域甲型流感病毒NA基因序列,用MEGA 4.0软件进行基因进化分析,并用NJ法构建进化树;对NA基因核苷酸序列同源性及编码蛋白氨基酸序列进行分析.结果 2009年新型甲型H1N1流感病毒世界各地不同毒株间的NA基因同源性极高,达到99.5%～100%,但与以往甲型H1N1人流感病毒的NA基因差异较大.2009年新型甲型H1N1流感病毒与欧洲A/swine/H1N1的NA基因同源性高,达到89.6%～92.9%,且糖基化位点分布一致,分别在50、58、63、68、88、146、235和386位存在糖基化现象.另外2009年新型甲型H1N1流感病毒与A/chicken/H5N1的NA基因同源性也较高,达到83.6%～85.3%.绝大部分2009年新型甲型H1N1流感病毒的NA蛋白酶活性中心及周围相关位点氨基酸组成保守,仍然表现为R118、D151、R152、R225、E277、R293、R368、Y402、E119、R156、W179、S180,D199、1223、E228、H275、E278、N295和FA25,但丹麦、日本、我国香港及湖南分离到的4株病毒出现H275Y突变.2009年新型甲型H1N1流感病毒NA基因可能来源于欧洲A/swine/H1N1流感病毒,并与A/chicken/H5N1病毒有较近的亲缘关系.结论 2009年新型甲型H1N1流感病毒并非由以往人H1N1流感病毒逐渐进化而来,而是一种新型重排病毒,我国湖南地区发现的一株新型甲型H1N1流感病毒具有H275Y奥司他韦耐药变异.
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